High temperature grease



United States Patent 3,269,951 HIGH TEMPERATURE GREASE Thornton P. Traise, Chicago Heights, 111., assignor to Standard Oil Company, Chicago, Ill., a corporation of Indiana No Drawing. Filed Feb. 3, 1964, Ser. No. 342,273 12 Claims. (Cl. 25249.6)

This invention relates to lubricant greases and particularly relates to a novel grease thickener for lubricant greases destined for high temperature service.

I have now discovered that greases possessing outstanding high temperature properties and mechanical stability may be prepared with a thickener comprising the reaction product of an aromatic diisocyanate and a phenyl azoaniline compound. Such preparation is advantageously effected in the presence of a lubricant base or vehicle, and a particular advantage of the inventive composition is that a wide variety of lubricant bases may be employed therewith.

The aromatic diisocyanate reactant may be any one of the diisocyanates having at least one aromati ring in the molecule. Biphenylene diisocyanates having the following structural formula:

NCO

constitute particularly desirable aromatic diisocyanates. In the foregoing formula n is an integer of 0-4, R is an alkyl group of 1 to 18 carbon atoms, a phenyl group, halogen, or mixtures thereof, and R is hydrogen or an alkyl group of 1-4 carbon atoms. Examples of biphenylene diisocyanates include bitolylene diisocyanate (3,3'-bitolylene 4,4 diisocyanate), diphenylmethane-4,4'-diisocyanate, 3,3-dimethylidiphenylmethane-4,4-diisocyanate, xylenyl diisocyanate, diphenylxylenyl diisocyanate, etc. Substituted diphenylene diisocyanates such as dianisidine diisocyanate and dichloroxenylene diisocyanate may also be employed. The preferred aromatic diisocy-anate reactant is bitolylene diisocyanate (3,3-bitolylene-4,4-diisocyanate).

Monophenylene diisocyanates may similarly be used. These compounds have the general formula NCO NCO

where R is an alkyl group of 1-4 carbon atoms and n is 0-4. The Rs may be the same or difierent alkyl groups. Examples of monophenylene diisocyanates include the tolylene diisocyanates, which are available as 65 percent of the 2,4 isomer and 35 percent of the 2,6 isomer, as 80 percent of the 2,4 isomer and 20 percent of the 2,6 isomer, or 100 percent of the 2,4 isomer. Other monophenylene diisocyanates include metaphenylene diisocyanate, 2,4- tolylene diisocyanate dimer, and xylylene diisocyanate. Substituted monophenylene diisocyanates are also suitable, and these include methoxyphenylene diisocyanate, phenoxyphenylene diisocyanate, and chlorophenylene diisocyanate.

Polynuclear aromatic diisocyanates such as naphthalene diisocyanates may also be employed.

Phenyl azoaniline compounds are the other reactants necessary for preparing the inventive compositions. These compounds generally have the following structural formula:

R N: N- R zN wherein R is hydrogen, an alkyl group of 1-18 carbon atoms, a phenyl group, halogen, or mixtures thereof. Examples of alkyl phenyl azoalkylaniline compounds include 4-(0 tolylazo) o toluidine, p-tolylazo-4-o-toluidine, pethylphenylazo-4-m-toluidine, o-ethylphenylazo-4-o-toluidine, 4-phenylazo-l-naphthylamine, etc.

Oleaginous lubricant vehicles or bases which can be thickened with the inventive reaction products can be any of the known lu'bricants. In one embodiment the lubricant is advantageously prepared by reacting the aromatic diisocyanate with the phenyl azoaniline compound in situ in such a lubricant base. The reaction product can conveniently be prepared in this manner by making separate solutions or dispersions of diisocyanate in lubricant base and phenyl azoaniline compound in another portion of the base material. The two separate solutions are then brought into contact in the presence of a catalyst material. Suitable catalysts are trialkyl amines having the following formula:

B N R.

wherein R is an alkyl group of l8 carbon atoms. Catalysts of this type include amine compounds such as trialkyl amines, e.g. triethyl amine which is preferred. In addition to amines, heterocyclic amines, such as pyridine, may be employed; phosphines may also be employed as catalyst materials. The reaction is carried out over a wide variety of conditions. For reasons of convenience the reaction may advantageously be carried out at room temperature and atmospheric pressure. The reactants are suitably reacted in proportions to give a ratio of 1 to 2 moles of phenyl azoaniline compound to 1 mole of aromatic diisocyanate. Preferably the reactants are contacted with each other in the ratio of 1 mole of phenyl azoaniline compound to 1 mole of aromatic diisocyanate.

Lubricant vehicles suitable for use according to the present invention are silicone polymer oils, mineral lubricating oils, synthetic hydrocarbon lubricating oils, synthetic lubricating oils such as the polyalkylene glycols and their derivatives, high molecular weight esters of dicarboxylic acids, polyfluoro derivatives of organic compounds such as the trifluorovinyl chloride polymers known as Fluorolube and the trifluorochloroethylene polymers known as Kel-F, etc. may be used.

. Greases prepared with thickeners of the type described above, particularly those prepared from silicone oil, are exceptionally stable at elevated temperatures.

The silicone polymer oils which may be employed in accordance with the present invention are those falling substantially within the lubricating oil viscosity range. In general, such oils have the following unit structure:

wherein R and R represent substituted or unsubstituted alkyl, aryl, alkylaryl, arylalkyl or cycloalkyl radicals. Such compounds may be produced by well-known methods, e.g. the hydrolysis of dialkyldichlorosilanes or dialkyldiethoxysilanes with a suitable chain stopper, e.g. a trisubstituted mono-chlorosilane. For purposes of the present invention, those polymers which are high boiling liquids within the lubricating oil viscosity range are suit- 3 able, these generally possessing a viscosity at 100 F. which is within the range of from about 25 to about 3500 S.S.U. It is preferred, for purposes hereof, to employ such oils as have a viscosity at 100 F. of from cant vehicle, heating to about 450 F. for a relatively short time, e.g. from about five minutes to an hour to drive off volatile by-products, and then cooling and milling the mixture.

about 300 S.S.U. to about 1250 S.S.U. Such products 5 (3) As a slight modification of method 2 above, a are generally colorless and inert, have a very low volatility solvent such as dioxane may be employed as a diluent and and undergo relativelyslight change in viscosity for a mutual solvent for the reactants. The solvent is then given change in temperature. Relatively common oils of evaporated and the grease is milled, etc. substantially as this type are dimethylsilicone polymer, phenylmethylset forth. silicone polymer, chlorophenylmethylsilicone polymer, (4) As a step in any of the above three methods, it etc., it being preferred to employ the phenylmethylsilicone has been found, when employing a silicone vehicle, that polymer in accordance herewith. Methods of preparing improved properties may be imparted to the grease by such compounds are taught in numerous patents, e.g. heat-treating the grease mixture, i.e. subjecting same to U.S. 2,410,346, U.S. 2,456,496, and in the literature such a temperature of about 450 F. for at least about half an as Chemistry of the Silicones by Rochow, page 61, hour and preferably longer, e.g. from about 1 to 30 hours. et seq. A particularly desirable phenylmethylsilicone Prolonged heating at such temperature may evaporate a polymer for use in accordance with the present invention portion of the lubricant vehicle; this loss should be reis Dow-Corning 550 silicone fluid, a product of Dowplaced and then the mixture should be milled. If desired, Corning, Inc., which has a viscosity at 100 F. of about the heating and readdition of vehicle may be repeated be- 300 to about 400 S.S.U. Also advantageous is Dowfore milling. Corning QF67024 fluid typically having a viscosity at The thickening compositions of the present invention 77 F. of 600 S.S.U. and a viscosity of 20 S.S.U. at are surprisingly efficient and they can be used to make 210 F, greases which are stable at high temperatures. To demon- Other oleaginous vehicles which may be employed herestrate the efiiciency of greases thickened with phenyl azowith are, for example, mineral oils in the lubricating oil niline-aromatic diisocyanate reaction products a number viscosity range, i.e. from about 80 S.S.U. at 100 F. to of grease compositions were prepared and tested. Table about 300 S.S.U. at 210 F. These mineral oils are 1 sets forth penetration data on the inventive composipreferably solvent extracted, to substantially remove the tions.

TABLE 1 Thiekener Grease Reactants Oil Penetration" Proportions, Thlckener,

mole wt, percent Azo Compound Dilsocyanate Unworked Worked 4- (o-t olylazo)-o-toluidine.

Blto lylene dllsocyanate n *ASTM D-217.

low V.I. constituents, e.g. aromatics, with phenol, furfural, B,B'-dichlorodiethylether (Chlorex), liquid S0 nitrobenzene, etc. Synthetic lubricating oils resulting from polymerization of unsaturated hydrocarbons or other oleaginous materials within the lubricating oil viscosity range such as high molecular weight polyoxyalkylene compounds such as polyalkylene glycols and esters thereof, aliphatic diesters of dicarboxylic acids such as the butyl, hexyl, 2-ethylhexyl, decyl, lauryl, etc., esters of sebacic acid, adipic acid, azeleic acid, etc., may be thickened by the compounds of the present invention to produce excellent greases. Polyfluoro derivatives of organic compounds, particularly hydrocarbons, in the lubricating oil viscosity range have shown excellent promise when thickened with compounds of the present invention. In addition synthetic ester vehicles and polyphenyl polysiloxanes may also be employed.

The lubricant vehicles herein described may be thickened to grease consistency typically by the addition thereto of from about 5 to about 70 percent by weight and preferably from about 5 to about percent by weight of the aromatic diisocyanate-phenyl azoaniline reaction product.

Greases of the present invention may be produced by one of the following methods:

(15) The thickener may be prepared apart from and then admixed with the lubricant vehicle and milled in a colloid mill, 3-roll mill, etc.

(2) The thickener may be formed in situ in the oil by introducing the reactants and the desired amount of lubri- A grease composition was prepared by thickening Dow- Corning 550 fluid with 9.5% of the product of reacting 4-(o-tolylazo)-o-toluidine and bitolylene diisocyanate. The grease was heat treated at 450 F. for 21 hours. Leakage loss for this composition after 24 hours at 450 F. was 6 weight percent. Evaporation loss after 24 hours at 450 F. was 2 weight percent. This composition was also employed to lubricate a lightly loaded antifriction bearing operated at a temperature of 450 F., under 50 pounds radial and 25 pounds axial loads at 10,000 r.p.m. The apparatus and test procedures used were in accordance with Coordinators Research Council test CRC L-35-59, the technique for which was developed and published by The Coordinators Research Council, 30 Rockefeller Plaza, New York 20, New York. In this test the bearing was successfully operated for 583 hours before failure. In addition at 543 hours of operation the bearing was heated to 600 F. for a period in excess of 1 hour. The same bearing test was run on two similar grease compositions prepared in the same manner except that one formulation contained 8 weight percent thickener and the other contained 10 weight percent thickener. Temperature at which the bearing test was conducted on these two compositions was 600 F. At this extremely high temperature the grease containing 8 weight percent thickener ran for 114 hours without failure and the grease containing 10 weight percent thickener ran for 116 hours Without failure.

Greases of the present invention may have added thereto anti-oxidants, oiliness agents, extreme pressure additives, etc., withou t in any way departing from the scope of the present invention.

Thus having described the invention, what is claimed is: 1. As a new composition of matter the product of reacting a phenyl azoaniline compound having the following structural formula:

wherein R is selected from the group consisting of hydrogen, an alkyl group of 1-18 carbon atoms, a phenyl group, halogen and mixtures thereof, with an aromatic diisocyanate in the ratio of from about 1 to about 2 moles of phenyl azoaniline compound per mole of aromatic diisocyanate.

2. The composition of claim 1 wherein said reacting is carried out in the presence of a catalyst having the following formula:

wherein R is an alkyl group of 1-8 carbon atoms.

3. As a new composition of matter the product of reacting an aromatic diisocyanate having the following structural formula:

wherein n is an integer of 0-4, R is selected from the group consisting of an alkyl group of 1 to 18 carbon atoms, a phenyl group, halogen, and mixtures thereof; and R is selected from the group consisting of an alkyl group of 1-4 carbon atoms and hydrogen; and a phenyl azoaniline compound having the following structural formula:

wherein R is selected from the group consisting of hydrogen, an alkyl group of 1-18 carbon atoms, a phenyl group, halogen, and mixtures thereof, in the ratio of from about 1 to about 2 moles of phenyl azoaniline compound per mole of aromatic diisocyanate.

4. The product of reacting 4-(o-tolyl-azo)-o-toluidine and bitolylene diisocyanate in the ratio of from about 1 to about 2 moles of 4-(o-tolyl-azo)-o-toluidine per mole of bitolylene diisocyanate.

5. A lubricant grease comprising an oleaginous lubricant vehicle thickened to grease consistency with the product of reacting a phenyl azoaniline compound having the following structural formula:

HgN

gen, an alkyl group of 1-18 carbon atoms, a phenyl uct of reacting an aromatic diisocyanate having the following structural formula:

R, NCO I C \l wherein n is an integer of 0-4, R is selected from the group consisting of an alkyl group of 1 to 18 carbon atoms, a phenyl group, halogen, and mixtures thereof; and R is selected from the group consisting of an alkyl group of 1-4 carbon atoms and hydrogen; and a phenyl azoaniline compound having the following structural formula:

NCO

wherein R is selected from the group consisting of hydrogen, an alkyl group of l18 carbon atoms, a phenyl group, halogen, and mixtures thereof, in the ratio of from about 1 to about 2 moles of phenyl azoaniline compound per mole of aromatic diisocyanate.

8. A lubricant grease comprising an oleaginous vehicle thickened with an amount of from about 5 to about percent by weight of the product of reacting an aromatic diisocyanate having the following structural formula:

wherein n is an integer of 04, R is selected from the group consisting of an alkyl group of 1 to 18 carbon atoms, a phenyl group, halogen, and mixtures thereof; and R is selected from the group consisting of an alkyl group of 1-4 carbon atoms and hydrogen; and a phenyl azoaniline compound having the following structural formula:

wherein R is selected from the group consisting of hydrogen, an alkyl group of 1-18 carbon atoms, a phenyl group, halogen, and mixtures thereof, in the ratio of from about 1 to about 2 moles of phenyl azoaniline compound per mole of aromatic diisocyanate.

9. The lubricant grease of claim 8 wherein the oleaginous lubricant vehicle comprises a silicone polymer oil in the lubricating oil viscosity range.

10. A lubricant grease comprising a silicone polymer oil in the lubricating oil viscosity range thickened with from about 5 to about 70 percent by weight of the product of reacting 4-(o-tolyl-azo)-o-toluidine and bitolylene 7 8 diisocyanate in the ratio of from about 1 to about 2 moles References Cited by the Examiner gig (:1Sg2-1ttg1yI-az0)-o-to1uidine per mole of bitolylene di- UNITED STATES PATENTS 11. The composition of claim 1 wherein said reacting iz g t hi e t l is rr'edot' th f ht 1' car a catii si u m 6 Presence 0 a e emcyc mine 5 3,133,883 5/1964 Hayne et a1. 252-s1.s

12. The composition of claim 5 wherein said reacting is carried out in the presence of a heterocyclic amine DANIEL E'WYMANPrlmary Examiner catalyst. I. VAUGHN, Assistant Examiner. 

8. A LUBRICANT GREASE COMPRISING AN OLEAGINOUS VEHICLE THICKENED WITH AN AMOUNT OF FROM ABOUT 5 TO ABOUT 70 PERCENT BY WEIGHT OF THE PRODUCT OF REACTING AN AROMATIC DIISOCYANATE HAVING THE FOLLOWING STRUCTURAL FORMULA:
 9. THE LUBRICANT GREASE OF CLAIM 8 WHEREIN THE OLEAGINOUS LUBRICANT VEHICLE COMPRISES A SILICONE POLYMER OIL IN THE LUBRICATING OIL VISCOSITY RANGE. 